Paper making



' April 12, 1927.

W. A. WHITCOMB PAPER MAKING Filed Feb. 28. 1925 s Sheets-Sheet 1 'vei ozt W 1. an;

1,624,029 i 1927' w. A. WHITCOMB PAPER MAKING Filed Feb. 28. 1925 s Sheds-Sheet 2 1,624,029 w, A. WHITCOMB PAPER MAKING Filed Feb. 28. 1925 3 Sheets-Sheet 5 April 12, 1927,

fi'lverlior, W CR H.

' Patented Apr. 12, 1927.

' UNITED STATES PATENT OFFICE.

WILLIAM A. WHITCOMB, OF DEDHAM, MASSACHUSETTS, ASSIGNOR TO GREAT NORTH- ERN PAPER COMPANY, OF MILLINOC'KET, MAINE, A CORPORATION OF MAINE.

PAPER MAxm.

Applicatiouflled February 28, 1925.

This invention relates to paper making and particularly to the drying of the-wet paper sheet after it leaves the paper making wire or other sheet forming means, and an object of this invention is the provision of a method and apparatus for drying the wet paper sheet; by the within the sheet itself.

The paper sheet after it leaves the sheet forming means. is more or less saturated with Water. Water, as commercially obtained, has a relatively low electrical resistance and consequently the wet paper sheet is a fair electrical conductor.- In carrying generation of heat out the invention, an electric current of suit able magnitude and at a suitable potential is caused to travelse'the wet sheet. Due to thewith a plurality of'spaced roll-electrodes of opposite polarity so that a lurality of rela. tively short conducting pat is are formed in the paper sheet, whereby to reduce the potential necessary to cause the requisite drying current to pass through the sheet.

A further object is generally to improve the construction of paper making apparatus and methods.

Fig. l is a more or less diagrammatic representation of the drier elements of a paper making machine embodying the inrent ion.

Fig. 2 is a side elevation. partly in section, of an electric drying roll of Fig. 1.

Fig. 3 is a section through the electric drying roll taken. along line 33 of Fig. 1-.

Fig. 4 is a view similar to Fig. 3 but taken along line H of Fig. 1.

Fig. 5 is an enlarged perspective detail illustrating the relation of the paper sheet and the electrodes of the electric drying roll of Figs. 1 and 2,

Serial No. 12,414.

Fig. 6 is a plan View" of one of the electrode rings of the drying roll.

Fig. 7 is a cross-sectional detail illustrating a modified construction of electric drying roll.

.Figs. 8 and 9 are side and end elerations respectively of a further modified form of electric drying roll, wherein the electrodes are spirally arranged on the surface of the roll.

Fig. 10 is a longitudinal sectional elevation through another form of drying roll wherein the electrodes are axially arranged on the periphery of the roll. F F 1g. 11 is a section along line 99 of Fig. 12 is an enlarged perspective detail illustrating the relation ofth'e paper, sheetand the electrodes of the electric drying roll of Fig. 10. i

Fig. 13 is an end detail of' the collector rings and brushes of the electric drying rolls illustrated in Figs. 2 and 10.

Fig. '1 illustrates more or less diagram-- maticall the drying end of a paper mak ing mac ine embodying the invention. The

wet paper sheet 16 coming from the Four drinier wire or other sheet forming means,

and press rolls, and, if desired, preliminary drying rolls of the ordinary type, not shown, passes over one or more lower and upper drying rolls "18 embodying the invention. Lower and upper felts 20 and 22 may he associated with the upper and lower rolls to support the wet paper sheet in contact with sai rolls in the usual manner. The construction and arrangement ofthese felts is.

well known and therefor need not be further described.

After passing from the electric drying rolls, the paper sheet may pass either to other driers of any desired type or direct to and through a calender stack, not shown, in the usual manner. 4

The electric drying rolls embodying the invention may be constructed in a- "ariety of Ways without departing from the principle of the invention. The preferred form of electric drying roll is illustrated in Figs. 1 through 6. Said roll is composed of a plurality of electrodes in the form of metalrings 24 and 26, which rings are arranged in alternate, parallel, spaced relation and are supported on a plurality of insulating of the sheet.

diametrically opposed tothe lugs 26. Said rings 24 and 26 may be identical in construction, and may be as illustrated in Fig. 6, and ma. the lugs ot the discs are disposed alternatel on diametrically opposed points of the rol All of said lugs 2i are adapted to be connected electrically to a conductor 34 which, in turn, is connected to a collector ring 36 carried by the shaft 32. All of said lugs 26 are similarly connected together and to a conductor 38, which conductor is connected to a second collector ring 40; Current at a suitable potential may be supplied to said rings from a suitable power source as the transformer 42 through brushes 44 bearing upon said collector rings. The wet paper sheet is adapted to be supported incontact with the periphery of said electrode rings for as large an extent of the periphery thereof as is practicable. Due to the alternate spacing of said electrode rings, a plurality of relatively short current conducting paths are formed through the wet paper sheet as illustrated in Fig. 5

Due to the current passing through the wet paper sheet and the resistance of the water content of the paper sheet,- the water becomes heated and is vaporized and driven '05, thereby effecting the drying of the paper.

Since the heating current passes through the paper sheet, the drying action proceeds simultaneously within the entire thickness As the rings are always in contact with the sheet, the circuit between the rings and through the sheet is never interrupted so long as there is a sheet on the roll, so that there is no danger of' damage to the sheet due to possible arcing. Preferably said rings are relative] thin so that their lines of contact with t- 9. upper sheet are relatively narrow and do not materially shield the paper sheet from the heating and drying action.

Preferably the interstices between said discs are filled in with some suitable insulating material as the insulating rings 46 so that the perpiphery of the drying 'roll is smooth and is adapted to support the paper sheet throughoutsubstautially its entire width. Said electrode rings and insulating rings may be suitably secured together by means of tie-bolts 48 which pass throu h said rings and are insulated from said e ectrode ringsby the insulating tubes 5.

be assembled in the roll so that mg rings ant said electrode rings so that ,said insulating rings are out of contact with said electrode rings for the greater part of their peripheral extent. Such a construct-Eon is illustrated in Fig. 7 where clearance slots 52 are provided between the insulating rings and the electrodes by means of the insulating spacing discs disposed on said insulating tubes 50 between said insulating rings and electrodes. Preferably the axial extent of said slots 52 is relatively small so that the paper will be adequately supported throughout its width.

Figs. 8 and 9 illustrate a modified form of electric drying roll wherein a plurality of spaced electrodes 24 and 26" are ar ranged in a more or less spxiral form about and imbcdded in the perip ery of an insulating cylinder 56. Alternate electrodes may be connected electrically together and to a suitable source of electric power in any desirable mannernot necessarily shown.

In the modification shown in Fi .10, the .electrodes comprise a lurality o axiallydisposed and periphera y arranged bars 24? and 26, which bars are secured at their ends to insulating discs 58 and 60 carried by the shaft; 62 and 64. The bars of said two sets are alternately arranged around the periphery of the roll and alternate bars as the bars 54 are connected electrically to a metal disc 66, which disc in turn, is connected to a conductor 68 and a collector ring 70 carried by theshaft 64. The other setof bars 26 is connected electrically ting similar disc 72, which disc is connected to a second collector ring 74 by means of a conductor 76. As arranged in this modification, the wet paper sheet 16 is supported upon the top edges of said electrode bars as is more clearly illustrated in Fig. 12 and a plurality of longitudinally-(1isposed current conducting paths are formed in the paper sheet. Preferably the topedges osa1d bars are reduced in area as at 76 for the pur se of reducing the area of contact of sai bars with the pa )er sheet.

. n addition to the dissipation of moisture in the wet paper sheet, due to the electrical heating thereof,'moistura may alto be dissipated at the electrodes due to electrolysis of the water, the water breaking up into hydrogen and oxygen in the usual manner.

The conductivity of water varies considerably and depends more or less upon the nature and amount of impurities therein. In some localities and under some circumstances, it may be that the water used to float the pulp stock and thereby present in the wet paper sheet has such a high resistance that an undesirably high potential may be required to effect the proper drying action. Under such circumstances, I may introduce tent.

a suitable amount of an electrolyte in the water whereby to increase the conductivity therein and thereby reduce the potential reto effect the drying of the paper sheet under specific conditions. I prefer to use two or more drying cylinders and to arrange them in such a manner with respect to each other and to the paper sheet that the lines of contact of the electrodes of the successive cylinders with the paper sheet wi fall between the lines of contact of the electrodes on the preceding drying cylinder, or the current paths formed in the paper 'sheet by the two rolls will overlap, whereby to avoid formation of water streaks in the paper sheet.

The potential of the current must be chosen to suit the work to be done and, the conductivity of the sheet and its water con- This may be determined by experiment. The drying proceeds more ra idly at high potentials, and with the use of proper precautions which will be familiar to any electrician a potential of more than 1000 volts may be employed but if the conductivity of the sheet is suflicient it is lower potential.

I claim: 1. The method of (1 ing a wet paper sheet which consists in con noting through it an electric current of such value as directly to heat and evaporate moisture in'the sheet. p

the combination of means to provide a plu- 2. The method of drying a wet paper sheet which consists in forming the sheet with the aid ofan electrolyte, and conducting through the wet sheet an electric current of such value as to heat and dissipate moisture therein.

3. The methodof drying a moving wet paper sheet which consists in passing the sheet over and in contact with spaced electrodes and conductingthrough-the moving sheet and between the electrodes an electric current of a magnitude sufficient to dissi pate moisture from the sheet by its direct' action on the wet sheet. a I

4. The method of drying amoving wet paper sheet which consistsin passing the sheet over and in contact with spaced electrodes, moving said electrodes with the moving sheet and conducting through thesheet and between the electrodes an electric current of a magnitude sufficient to dissipate moisture from the sheet.

5. The method of drying a moving wet paper sheet which consists in passing the paper sheet about a. roll having a. plurality of peripherally spaced electrodes which supportand are in contact with, the sheet on the roll, and conducting through the paper sheet between the electrodes an electric current of suflicient magnitude to dissipate moisture from the sheet.

- fish a difference of desirable to use a i 6. A paper drier comprising a roll adapted to support and drive a wet paper sheet and including a plurality of peripherallydisposed and axially-spaced, electrically-conducting rings adapted to engage and support the \vetpaper sheet, and means to estab potential between groups of said rings.

7. A paper drier comprising a roll adapted to support and drive a wet paper sheet comprising a plurality of peripherally-disposed and axially-spaced. electrically-conducting rings adaptedto engage and support the wetpaper sheet. means to connect alternate rings electrically. and means to establish a difference of potential between said alternate rings.

8. A paper making machine comprising the combination of means to establish a plurality of electrically-conducting current paths through a wet paper sheet. and means to pass through said paths electric currents of magnitudes sufficient to effect the-heating and dissipation of the moisture in the current paths. y

9. A paper making machine comprising. the combination of means to establish a pluralitv of overlapping and electrically-conducting current paths through a wet paper sheet, and means to pass through said paths electric currents of magnitudes sufficient to effect the heating and evaporation of the moisture in the current paths.

10. A paper making'machine comprising rality of successive and overlapping electrically-conducting currentpaths through a wet paper sheet, and means to pass through said paths electric currents at sufficient magnitude to effect the heating and drying of the weth paper sheet included in said current pat s. v

11. A paper making machine including two electric drying rolls about which the wet paper sheet is adapted to be supported and passed, each roll having a plurality of spaced peripheral electrodes which electrically engage said wet paper sheet, and. form a plurality of current-conducting paths through it, said rolls arranged to provide overlapping. c0nducting paths in the wet sheet, means to pass the wet paper sheet about said rolls in succession. and means to pass electric currents through the conduct ing paths in the wetsheet. 12.An electric paper drier including a pair of spaced electrodes arranged electrically to engage a moving wet paper sheet. and means to maintain the continuity of the electrically conducting path through the moving paper sheet between said electrodes. 13. Anelectric paper drier including a drying roll having a relatively smooth periphery adapted to support the wet paper width, and a plurality of insulated elec:'

]y-disposed and spaced electrodes arranged to support and also to electrically engage the wet paper sheet, and other paper-supporting means disposed between said electrodes.

15. An electric paper drier including a drying roll including a plurality of peripherally-disposed and spaced electrodes arranged to support and also to electrically engage the wet paper sheet, and other papersupporting means comprising insulating members disposed between said electrodes.

16. An electric paper-drying roll including a plurality of alternately-disposed insulating and conducting members arranged to provide a smooth and substantially continuous paper-supporting surface, and means to electrically connect alternate conducting members.

17. An electric paper-drying roll includ ing a plurality of alternately-disposed insulating and conducting rings arranged to provide a smooth and substantially continuous paper-supporting surface, and means electrically to connect alternate conducting members. 7

In testimony whereof, I have signed my name to this specification.

WILLIAM A. WHITCOMB. 

